Pope Paul VI
Sacerdotalis Caelibatus §49
Sacerdotalis Caelibatus: On the Celibacy of the Priest
49 We are not easily led to believe that the abolition of ecclesiastical celibacy would considerably increase the number of priestly vocations: the contemporary experience of those Churches and ecclesial communities which allow their ministers to marry seems to prove the contrary. The causes of the decrease in vocations to the priesthood are to be found elsewhere—for example, in the fact that individuals and families have lost their sense of God and of all that is holy, their esteem for the Church as the institution of salvation through faith and the sacraments. The problem must be examined at its real source.
Source: Sacerdotalis Caelibatus (Vatican.va)